This invention relates to a controller for trimming copy sheets from a material (paper) web in a copying machine, and particularly a keypad therefor. Specifically, the present invention relates to controlling a trimming device wherein the width of the margins of the original document and the intended width of the margins of the copy sheet are indicated by keypad settings to which the trimming device is responsive for providing a sheet of appropriate size onto which the copy is developed.
An example of a copying machine employing a trimming device and a controller of this type is disclosed in the German patent disclosure No. 31 43 112. There, the copy sheet is trimmed from a material web in accordance with the settings on the keypad to indicate the width(s) of the margin(s) of the leading and/or trailing edge of the original and the copy. In keypads of this type, the width of the leading and/or trailing original document margin (OR.sub.L, OR.sub.T, respectively) and the width of the desired leading and/or trailing copy sheet margin (PR.sub.L, PR.sub.T, respectively) are entered and stored. A control unit comprises a device for sensing the leading and trailing edge of the document at a specific spacing A in the feed direction of the document ahead of the trimming device. Control pulses are emitted when the leading or trailing edge of the document has traveled the distance A.+-.(PR-OR).sub.L,.sub.T from the sensing device. The pulse triggered by the leading document edge controls the advance of the material web, and the control pulse triggered by the trailing document edge actuates the trimming device for severing the copy sheet. The margin widths of the copy are generally dimensioned from the margin widths of the original document and are thus of the desired widths.
One disadvantage of this prior device is that the leading and trailing document margins must be measured and their dimensions separately entered. Alternatively, other input elements may be required to assist in entering the correct margins. Further, the measuring operation and the subsequent entering are in the nationally applicable unit of measure (e.g., metric). Hence, exporting the device to countries using nonmetric measuring systems necessitates additional conversion circuits which convert the entered margin widths to the measuring system in which the specific distance A is specified.
It has been one objective of the present invention to provide a controller for a copying machine trimming device with a keypad wherein the width of the document margins can be entered dependably and in a simple manner without a separate measuring operation.
A further objective of the present invention has been to provide a controller for a copying machine trimming device with a keypad wherein the width of the document margins is entered independent of the applicable unit of measure.